Unable to login after restoring a Confluence backup (Bug???) Edited

I have made a backup with all attachments in Confluence 6.2.3. Then I have setup a complete new installation with Confluence 6.3.1 and switched from Postegres 9.5 to 9.6.

I configured the new installation and connected to my JIRA 7.4.0 user database - everything is fine, I can login, etc.

But after I restored my backup in Confluence I cannot login anymore. The restoring process was fine, no errors where shown. I was thrown back to the login screen of Confluence, but I cannot login anymore.

When I try to reset the password via email I received an email to reset my password. After I entered a new password a Confluence Error was thrown:

After I restored the backup, there is still the "You have temporary access to administrative functions. Drop access...." in the header. I will not disappear. It is always there.

And I did a new installation with all users managed by Confluence - no JIRA connection to the user data base.

First I did a c lean installation with the embedded Confluence database - the import works fine! I exported the database again, so I have got a 6.3.1 backup.

Now I did a clean installation 6.3.1 based on a Postgres 9.6.3 database. All user managed by Confluence. Everything is working fine. But when I imported my 6.3.1 backup - the same problem. I cannot log in anymore, "Drop access" in the header, it is not possible to reset the password, error like above...